Gas turbine engines, also known as jet engines, may be used for power generation and propulsion of a vehicle (e.g., an aircraft). The engine may include a compression section, a combustion section, and a turbine section that utilize a primary airflow into the engine to generate power or propel the vehicle. The engine may be mounted within a housing (e.g., a nacelle of the aircraft). A bypass airflow passage may be defined between the housing and the engine. A bypass airflow may flow through the bypass airflow passage and exit from an outlet of the housing.
As engine bypass ratios increase, it may become increasingly difficult to maintain a suitable bypass pressure ratio, for example, to avoid fan flutter of the engine. Variable area fan nozzle systems may be used to maintain a desired pressure ratio, however, such systems tend to be very complicated and add additional weight to the aircraft.
Thrust reversers may be used to generate a reverse thrust force to slow forward movement of the aircraft. One type of thrust reverser may utilize a moveable door located near a rear of the nacelle. The door may move into the bypass airflow passage to deflect the bypass airflow radially outwards through a reverse thrust opening to direct a discharge airflow in a forward direction to slow the aircraft. Although thrust reversers effectively slow the aircraft, thrust reversers typically serve only that purpose and do not provide any additional functionality when not in use.
Accordingly, those skilled in the art continue with research and development efforts in the field of controlling the bypass airflow through the aircraft engine system.